Inspection of multilayer ceramic circuit modules by electrical inspection of unfired green sheets

Abstract

A method of manufacturing packages for LSI chips starts with the usual steps of punching holes in green sheets, screening patterning paste (adapted to form cermet conductors or the like after firing) onto the green sheets, and inspecting the green sheets optically. Here, subsets of green sheets are then stacked and compressed into sublaminates. The sublaminates are then functionally inspected electrically. Inspection is done by means of electromechanical contact, scanning electron microscope like techniques, or by other means of irradiating the conductors to energize them for electrical measurement. Measurement may be made between pairs of terminals on only one side of the device being tested, or on both sides of the device. Beams can be applied both top and bottom from a single source or plural sources. Measuring instruments employ various electromechanical techniques as well as electrons, light used photoelectrically, ions, or pneumatic ion jets. Secondary electrons can measure the specimen's potential locally or change its charge. This method can also be employed for the purpose of inspecting other multilayer structures (such as large multilayer printed circuits formed on a plastic base) prior to final assembly of the conductors and the various substrates into a laminated support for electrical circuits. This testing process can also be applied after firing of patterned green sheets prior to plating, as well as after plating.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent is: 
     
       1. In a method of manufacture of ceramic electronic substrates comprising, applying a paste to a number of unfired ceramic sheets,   said paste being applied in a manner adapted to form ulimately electrically conductive patterns after firing,   the improvement comprising electrically inspecting at least one of said ceramic sheets with an electrical input applied directly to said sheets prior to the step of firing of said sheets.   
     
     
       2. A method in accordance with claim 1 including passing a current through said paste and   applying an electrical measuring apparatus to measure said current.   
     
     
       3. A method in accordance with claim 1 including passing a current through said paste   applying an electrical measuring apparatus to measure said current by means of electromechanical contact.   
     
     
       4. A method in accordance with claim 1 including passing a current through said paste   applying an electrical measuring apparatus to measure said current by means of nonmechanical electrical inspection.   
     
     
       5. A method in accordance with claim 1 including said paste including at least two terminals,   irradiating one of said terminals of said paste with a beam to electrically stimulate said paste,   irradiating a different one of said two terminals with a beam to sense an electrical response at said different terminal.   
     
     
       6. A method in accordance with claim 1 including said paste passing through said sheets providing an end at each surface of a said sheet,   applying a first electron beam to one end of said paste   scanning the opposite end of said paste, and   detecting the emission of secondary electrons emmitted from said opposite end to determine the electical conduction or interruption through said electrical connections.   
     
     
       7. A method in accordance with claim 1 including said paste passing through said sheets providing an end at each surface of a said sheet,   charging without mechanically contacting one end of said paste to give charge using a first electron beam,   directing without mechanically contacting another portion of said paste a second electron beam to generate secondary electron beam emissions, and   discriminating by detecting the variation in energy level of secondary electrons emitted and their intensity to determine whether said electrical connections have electrical continuity or are open.   
     
     
       8. A method in accordance with claim 1 including said paste passing through said sheets providing an end at each surface of a said sheet,   irradiating one end of said paste on one side of said sheet with a first electron beam to charge said paste and said electrical connection to a given potential,   generating a second electrical beam on an opposite side of said sheet to cause secondary electron emission from said paste which is at said given potential, and   detecting the presence of conductors not at a given potential.   
     
     
       9. A method in accordance with claim 1 including said paste passing through said sheets providing an end at each surface of a said sheet,   applying an electron beam to one side of sheet to one end of said paste on one side of said sheet with a first electron beam,   generating a steerable electron beam on the opposite side of said sheet, and   detecting the emission of secondary electrons emitted from said opposite surface to determine electrical conduction or interruption through said paste.   
     
     
       10. A method in accordance with claim 1 including said paste passing through said sheets providing an end at each surface of a said sheet,   irradiating an electrical conductor formed from said paste on a said sheet to charge said paste to a given potential,   irradiating a beam at a different position on said sheet to cause emission from the paste at said different position.   
     
     
       11. A method in accordance with claim 10 including said one position and said different position being on opposite sides of said material.   
     
     
       12. A method in accordance with claim 1 including charging without contacting conductors formed of paste on one side of a sheet to a potential using a first electron beam,   directing a second electron beam to generate secondary electron emissions at a portion of said conductor on the opposite side of said sheet without contacting the opposite side of sheet,   discriminating by detecting the variation in energy level of secondary electrons and their intensity to determine whether said electrical conductors have electrical continuity or are open.